This monograph is the sixteenth in a series of historical studies dealing with USAF plans, policies, and operations in Southeast Asia, published under the general title, The Air Force in Southeast Asia. Its focus is on Air Force participation in the last tempestuous year of US involvement in the war in Vietnam when, after the great majority of US forces had been withdrawn, Hanoi launched its smashing Easter offensive. This study relates how air, as almost the sole remaining US weapon, played a complex and varied role. This consisted not only of its key part in the military operations which turned back the enemy offensive, but also of its influence on the negotiating process and its exercise of a "persuasion" role for US diplomacy. In writing this monograph, the author found a lack of sources not encountered in previous monographs in this series. The important peace negotiations of 1972 and the decisions and communications pertaining to Linebacker II operations were all kept highly secret. Almost no official accounts of them are available, either in JCS, Defense, Air Force, or State Department records. These matters were dealt with only at the highest levels, and many researchers believe this was done orally with decisions not committed to paper. Since the Nixon and Kissinger papers will not be available for many years, this study has utilized certain detailed and seemingly reliable secondary sources to fill in some of the information gaps, until such time as the full story is available from official records.